Rockwell Automation 8520-MUM 9/Series CNC Mill Operation and Programming Manual Documentation Set - Manual (Page 586)

Using Pocket Milling Cycles
Chapter 22
22-14
Figure 22.5
Circular Pocket Enlarging Using G88.1
EXISTING
POCKET
Q
Plunge Position
D D D (X, Y)
R
Y
X
Important: The tool should be positioned near the center of the pocket
prior to the G88.1 block. The Z coordinate of this position determines the
initial Z level or top of the pocket. This is the pre-cycle position of the
tool. The pre-cycle position must be at some depth other than the cycles
programmed final depth or an error is generated.
From the pre-cycle position, the control simultaneously raises the tool by
the clearance amount (AMP selectable, refer the literature provided by
your system installer) while moving it to the center of the original circular
pocket specified by the X and Y parameters. This simultaneous move
takes place at the rapid feedrate. The tool is then moved along the -X axis
to the left side of the original circular pocket. This position is the
plunge-position of the cycle.
After the plunge operation, the control performs a single-axis cut outwards
along the -X axis of the circular pocket. The control then moves the tool in
a 360 degree circular path that starts and ends at the -X axis.